1. Field of the Invention
The present invention relates generally to equipment used in the printing industry, and more particularly is an automated paper turner for a work and turn printing operation.
2. Description of the Prior Art
The printing industry requires a good deal of high cost capital equipment. Much of the cost of a given printing job is due to the expense of the printing presses. A simple, low end press costs $100,000, and a high end, multi-color press costs millions of dollars. Multi-color presses typically require more than one press operator—a head press man and at least one press helper. The head press man sets up the color and the registration, and the press helper feeds the paper. If a particular shop cannot afford the expense of the press helper, then the head press man does both the set-up work and the paper feeding. This situation significantly slows the pace of production.
Printing presses are also distinguished by whether they print on only one side of the paper on a given run (a straight press), or whether they print on both sides of the paper simultaneously (a perfecting press). The distribution of these machines in the printing industry is roughly 90%/10%, with the straight presses being the far more common machine. This means that the majority of printing work is done on a straight press, printing on one side at a time, even though most printing jobs require printing on two sides.
Therefore, most of the time a “work and turn” operation is required. That is, the first side is printed, then the paper is flipped over, and the second side is printed by running the paper through the same press a second time. The turning operation is generally accomplished manually, by either the head press man or the press helper. The turner must take the stack of paper printed on one side back to the feeding area at the rear of the press, turn the paper, usually in stacks of two to three inches, and feed the paper back into the press. This is clearly a time consuming operation, and if there is only a single press operator, the operator has to monitor the colors and the registration while feeding the press. This arrangement slows the operation and can adversely affect the print quality.
The prior art automation solution for the work and turn operation is a hydraulic turning machine. The hydraulic turning machine clamps the paper to be turned tightly on both the top and bottom of the paper, lifts the stack of paper, and turns it. This is a costly solution to the work and turn problem, in that the automatic turning machines cost from $17,000 to $30,000. Moreover, the automatic turning machines can create yet another problem. The pressure used by the machines to secure the paper can offset the print if the printed material is not allowed to thoroughly dry before the turning operation. If you turn the printed paper too soon, the work is destroyed. If you wait too long for the ink to dry, delay is introduced into the printing process.
One more economical method of automating the turning process to some degree is found in co-inventor Malakiman's U.S. Pat. No. 6,626,631, “Paper Turner for Work and Turn Printing Operation”, issued Sep. 30, 2003. The Malakiman device includes a pair of slides to hold a paper stack, the slides being mounted on a pair of parallel tracks. To turn the paper stack, the paper turner is positioned so that a first slide is under the pallet on which the paper stack rests. The second slide is lowered to rest on top of the paper stack, and the slides are locked in position relative to each other. The paper turner is then turned, using wheels to support the weight, until the paper stack is in a substantially horizontal position. The slides and the stack are then moved to the opposite end of the tracks. The paper turner is again rotated until it is in a vertical orientation, rotated 180° from its original position. The printed sides of the paper are now facing downward, and the paper is ready to be loaded into the printing press to print the second side. While the Malakiman device is easy to use and inexpensive, a work and turn operation using the Malakiman device does still entail a good deal of manual labor.
Accordingly, it is an object of the present invention to provide a method of fully automating the work and turn operation.
It is a further object of the present invention to provide a turning mechanism that allows the turn operation to be completed immediately after the first printing run without a likelihood of offsetting print, even if the paper is turned before the ink has dried.
It is a still further object of the present invention to provide an automated turning machine that is relatively inexpensive, and that is easy to use.